FE Environmental Part 5

Flashcards from the notes I've taken in preparation for the Environmental FE. This covers these topics: probability/statistics, fluid mechanics/hydraulics, mathematics

mode

value in a data set that repeats most frequently

median

middle value in data set

mean

average of all numbers in a data set

range

difference between max and min values in a data set

variance

average squared deviation of each point in a data set from the mean

standard deviation

square root of the variance in a data set

0 and 1

probability of an event is always between…

mutually exclusive

events cannot occur at the same time

independent

one event occurring does not affect the likelihood of the other event

conditional probability

probability that event B occurs given that event A has already occurred

random variable

variable whose observed value is determined by chance

discrete random variable

random variable whose set of possible outcomes is countable

continuous random variable

random variable that takes on any value over a continuous scale

law of sines

use for triangle when one side-angle pair is known

law of cosines

use for non-right triangles

polynomial roots

occur where the graph crosses the x-axis

integral

represents area under curve, total mass, and total flow volume

differential equations

contain derivatives of unknown factors

precision

how close repeated measurements are to each other

accuracy

how close a measurement is to its true value

buoyancy

ability of something to float in a liquid

Reynolds number

number that determines flow regime

Moody diagram

diagram used to determine friction factor

lower

smooth pipes have ____ friction

higher

rough pipes have ____ friction

open channel flow

flow with free surface exposed to atmosphere

Froude number

number that determines flow regime

culverts

closed conduits that flow partially full

pumps

devices that convert mechanical energy into fluid energy

pump head

energy added by pump

60-90

pump efficiency is usually between __ and __ %

pump operating point

intersection of pump and system curves; flow rate occurs here

pumps in series

used when more pressure is needed in pumps; flow remains the same

pumps in parallel

used when more flow is needed in pumps; head remains the same

orifice meter

opening used to control/measure flow by creating a constriction in the system

weir

barrier used to control flow, manage water levels, and measure discharge

flume

channel used to measure water flow in open channels

blower

used to move air and gas

blower operating point

intersection of blower and system curve

blowers in series

results in pressure increase in blowers

blowers in parallel

results in flow rate increase in blowers

uniform flow

depth and velocity remain constant along channel

non-uniform flow

depth changes along flow

21%

what percent of the atmosphere is oxygen?

78%

what percent of the atmosphere is nitrogen?